1. Field of the Invention
The present invention relates to a folded fin forming method, machine and folded fin obtained therefrom. The folded fin has a corrugated configuration and is particularly used in constructing a heat sink for dissipating heat generated by Integrated Circuits (ICs).
2. The Prior Art
Due to the increased consumption of power of ICs (particularly Central Processing Units (CPUs)), heat dissipation of these electronic components is becoming increasingly important. To solve this problem, heat sinks are mounted to contact the CPUs to absorb heat generated thereby and dissipate it into the surrounding air.
Referring to FIG. 1, a conventional heat sink 10 is constructed by aluminum extrusion to have a number of heat dissipating fins 12. The heat sink 10 formed by this method is costly.
To lower the cost, a folded fin 22 having a corrugated configuration is made by stamping or roll forming a metal sheet (usually an aluminum sheet), as seen in FIG. 2. The folded fin 22 consists of a number of inverted U-shaped heat dissipating fins 23 and is fixed to a flat base plate 24 by epoxy or riveting to form a heat sink 20.
The heat sinks 10, 20 made in accordance with the prior art share a common disadvantage. Each of the heat dissipating fins 12, 23 cannot have an aspect ratio (H/W) larger than twelve, otherwise breakage of the fins 12, 23 will occur during manufacture of the heat sink 10 or the folded fin 22. The limited aspect ratio of the fins 12, 23 limits the available heat dissipating area per length unit of the heat sink 10, 20.
Moreover, referring to FIG. 3, in order to enhance the heat dissipating effectiveness of the folded fin 22, when producing the folded fin 22 by roll forming, a number of louvers 252 are defined in webs 25 of the heat dissipating fins 23. Due to the limitation of the forming direction of the roll forming, the louvers 252 can only be vertically defined in the webs 25. Although the louvers 252 can increase the heat dissipating area of the folded fin 22, the direction of arrangement of the louvers 252 is perpendicular to the direction of forced air flow through the heat sink. Thus, the enhanced effectiveness achievable by the provision of the louvers 252 is not as significant as horizontal louvers.
Hence, an improvement over the prior art heat sink is needed.